US3913626A - Fluid flow ducts - Google Patents

Fluid flow ducts Download PDF

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Publication number
US3913626A
US3913626A US352921A US35292173A US3913626A US 3913626 A US3913626 A US 3913626A US 352921 A US352921 A US 352921A US 35292173 A US35292173 A US 35292173A US 3913626 A US3913626 A US 3913626A
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US
United States
Prior art keywords
members
duct
fluid flow
flow area
edges
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US352921A
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English (en)
Inventor
David Roberts Mcmurtry
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rolls Royce PLC
Original Assignee
Rolls Royce 1971 Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rolls Royce 1971 Ltd filed Critical Rolls Royce 1971 Ltd
Priority to US05/551,980 priority Critical patent/US3967443A/en
Application granted granted Critical
Publication of US3913626A publication Critical patent/US3913626A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02K—JET-PROPULSION PLANTS
    • F02K1/00—Plants characterised by the form or arrangement of the jet pipe or nozzle; Jet pipes or nozzles peculiar thereto
    • F02K1/06—Varying effective area of jet pipe or nozzle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15D—FLUID DYNAMICS, i.e. METHODS OR MEANS FOR INFLUENCING THE FLOW OF GASES OR LIQUIDS
    • F15D1/00—Influencing flow of fluids
    • F15D1/02—Influencing flow of fluids in pipes or conduits

Definitions

  • This invention relates to fluid flow ducts. It is sometimes desirable to alter the cross-sectional fluid flow area of a duct. For example, to match the operating characteristics of a ducted fan gas turbine engine to the flight envelope of an aircraft in which it is installed it is desirable to be able to alter the cross-sectional area of the nozzle at the downstream end of the duct. It is known to use inflatable elastic members to vary the flow area of a duct, but in prior proposals the members were stretched in their operative positions and thus subject to fatigue.
  • a fluid flow duct comprises at least one wall defining the duct, a flexible sheet material member attached to the wall and means for changing the shape of the member between a first convex position and a second concave position for varying the cross-sectional flow area of the duct, wherein in said concave position the member lies in a recess in said wall, and both positions constitute unstretched positions of the member.
  • the fluid flow duct may be a fan duct of a ducted fan gas turbine engine comprising a fan cowl defining aradially outer duct wall, a centerbody defining a radially inner duct wall, a member attached to the centerbody and means for changing the shape of the member between a first, convex position and a second, concave position.
  • the member follows the general shape of the centerbody, and in the concave position the member adopts the shape of the recess.
  • the member is preferably made in a flexible material and the first and second positions correspond to natural unstretched states of the member.
  • the ducted fan gas turbine engine may be of the variable pitch fan type, and the fan cowl, andone or more members attached to the centerbody may be so arranged that together they form a nozzle at one end of the duct.
  • the cross-sectional flow area of the nozzle may be altered according to the position of each of the members.
  • the nozzle may act as an intake when used with a variable pitch fan gas turbine engine operating in the reversed pitch mode.
  • FIG. 1 is a longitudinal section through a gas turbine engine, including the duct of the present invention
  • FIG. 2 is a view on the line I-I of FIG. 1,
  • FIG. 3 is a view on the line 11-]! of FIG. 2,
  • FIG. 4 is an expanded detail of a section on the line III-Ill of FIG. 3, and
  • FIG. 5 is a longitudinal section through a spool valve, for controlling the supply of compressed fluid to the members.
  • FIG. 1 there is shown a front fan gas turbine engine 11 comprising an outer fan cowl l2 spaced from a centerbody 13 by struts 14 to define a fan duct.
  • the cowl encloses a variable pitch fan 15 and a core engine 16 which is drivingly connected to the fan and is situated within the centrebody.
  • Such an engine may be used as a propulsion unit for an aircraft.
  • air enters an intake at 17, is compressed by the fan and delivered past a flow splitter I8 which divides the flow into two streams.
  • a first stream flows through the core engine 16 in which it is further compressed by an intermediate compressor 19 and by a high pressure compressor 21, before entering a combustion chamber 22, where it is mixed with fuel and burned.
  • the products of combustion flow through the several stages of a turbine 23 drivingly connected to the fan and the intermediate and high pressure compressors by shafts (not shown), and are then exhausted via the nozzle 24.
  • the second stream which provides the main propulsive force from the engine, is delivered to atmosphere via the duct 25 and the nozzle 20 defined by the downstream end of the fan cowl l2 and the centerbody 13.
  • each member is made of fibre-reinforced sheet rubber so that it is flexible but substantially inelastic, and is capable of being moved by means later described, between two positions including a first position 27 (shown in full lines in FIG. 1) in which it follows the general shape of the centerbody, and a second position 28 (shown in dotted lines), in which it lies flush with and is received in a recess which in this embodiment is in the form of a depression 29 in the centerbody. It will be understood that the recess may be merely a hole in the centerbody. In each of the positions 27,28 the member is substantially unstretched from its natural state.
  • each recess in the centerbody are blended gradually into the centrebody, as at 37, to prevent large deflections of the member along its line of attachment to the centerbody.
  • Attachment of the member to the centerbody is shown in FIG. 4 and may be achieved by bonding the edge 38 of each member into a metal channel section 39, the channel section 39 having internal ribs 40 which co-operate with ribs 41 on the member for retention thereof.
  • the member is connected to the centerbody by bolts 42. As illustrated, the edge 38 is bonded without sharp bends to prevent relatively high local stresses at the edge.
  • the members 26 have been described as being constructed from fibre-reinforced rubber, in an analogous manner to a pneumatic tire carcass, but it will be appreciated that synthetic material or a sheet of metal could be used.
  • synthetic material or a sheet of metal could be used for the member 26 in the case of a piece of sheet metal being used for the member 26 it would be formed by a pressing operation to produce, for example, the shape of the member in the convex position.
  • the edge of the member is rigidly clamped by bolts 42.
  • a force is applied perpendicular to the convex surface so that the sheet inverts into the concave position.
  • the concave position is the mirror image of the convex position so that both positions correspond to natural unstretched positions of the member.
  • the maximum nozzle area available For the conditions encountered during take off of an aircraft in which the gas turbine engine described above is installed, it is desirable to have the maximum nozzle area available, and thus at take-off all six members would lie in the second position 28.
  • the nozzle area required progressively decreases and this may be achieved by applying pressurized air to the underside of each of the members 26 in turn so as to move sequentially each member to the first position 27. It is preferable to have at least six members otherwise the sudden decrease in nozzle area as each member is sequentially moved to the first position may cause too sudden a pressure change in the duct 25 resulting in surging of the engine.
  • the members 26 are moved between the first and second positions by establishing a pressure differential across them. This is conveniently done using pressurized air from a compressor of the engine under the control of a spool valve 32 as shown in FIG. 5.
  • the Rayleigh pitot pressure As the forward speed of the aircraft increases the Rayleigh pitot pressure, as sensed by a pilot tube 33, increases and this pressure is communicated to a resilient bellows 34 connected to the spool valve 32.
  • a resilient bellows 34 connected to the spool valve 32.
  • the degree of expansion of the bellows is proportional to the forward speed of the aircraft and the movement of the spool valve may be used sequentially to connect a source of relatively high pressure air 35, for example bleed air from the LP. (intermediate pressure )compressor 19, to galleries 36, each gallery connecting with one of the depressions 29 in the centrebody.
  • a second spool valve not shown but otherwise identical to the first spool valve, working in reverse may be used sequentially to vent the pressure in each of the galleries 36.
  • the duct pressure will be sufficiently high to move each member 26 to the second position 28 once each gallery 36 has been vented.
  • a fluid flow duct comprising at least one central wall defining the duct and for which there is provided a plurality of flow area varying means on said central wall therein, said flow area varying means each comprising one flexible sheet material flow area varying member, means for attaching said flow area varying members by their edges to the periphery of respective recesses in the central wall, said members being deployable in operation in either of two positions including a first concave position in which said members are received in the respective recesses and a second convex position, said members being substantially unstretched in either of said two positions, said second convex position being the mirror image of the first concave position and selectively varying the flow area through the duct, the separate fluid pressure means operable on said members for changing the position of said members between said first and second positions wherein fatigue in the unstretched members is substantially re quizzed.
  • a fluid flow duct according to claim 1 wherein said edges are attached to the respective recesses without sharp bends at said edges to prevent relatively high local stresses at said edges.
  • a fluid flow duct according to claim 1 further comprising a plurality of flexible sheet material flow area varying members, each said member being attached by their edges to the periphery of a respective recess in the duct wall and wherein said pressure differential creating means includes means for creating the pressure differential across each member.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)
US352921A 1972-04-27 1973-04-20 Fluid flow ducts Expired - Lifetime US3913626A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US05/551,980 US3967443A (en) 1972-04-27 1975-02-21 Turbofan engine with flexible, variable area nozzle

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB1960572A GB1418665A (en) 1972-04-27 1972-04-27 Fluid flow ducts

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US05/551,980 Division US3967443A (en) 1972-04-27 1975-02-21 Turbofan engine with flexible, variable area nozzle

Publications (1)

Publication Number Publication Date
US3913626A true US3913626A (en) 1975-10-21

Family

ID=10132155

Family Applications (1)

Application Number Title Priority Date Filing Date
US352921A Expired - Lifetime US3913626A (en) 1972-04-27 1973-04-20 Fluid flow ducts

Country Status (6)

Country Link
US (1) US3913626A (enrdf_load_stackoverflow)
JP (1) JPS5723099B2 (enrdf_load_stackoverflow)
DE (1) DE2321432C2 (enrdf_load_stackoverflow)
FR (1) FR2182122B1 (enrdf_load_stackoverflow)
GB (1) GB1418665A (enrdf_load_stackoverflow)
IT (1) IT980381B (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4068469A (en) * 1975-05-29 1978-01-17 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Variable thrust nozzle for quiet turbofan engine and method of operating same
WO2008045057A1 (en) 2006-10-12 2008-04-17 United Technologies Corporation Bladder type variable area fan nozzle
CN107013268A (zh) * 2015-11-23 2017-08-04 通用电气公司 用于喷气发动机排气的压缩整流罩
US20180017020A1 (en) * 2015-02-11 2018-01-18 Mra Systems, Inc. Turbine engines with variable area nozzle

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB0312505D0 (en) * 2003-05-31 2003-07-09 Rolls Royce Plc Engine nozzle
DE102011106959A1 (de) * 2011-07-08 2013-01-10 Rolls-Royce Deutschland Ltd & Co Kg Fluggasturbine mit variabler Nebenstromdüse
DE102015206095A1 (de) * 2015-04-02 2016-10-06 Rolls-Royce Deutschland Ltd & Co Kg Fluggasturbine mit variabler Nebenstromdüse

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1873138A (en) * 1930-09-24 1932-08-23 Mitchell James Macdonald Valve structure
US2147031A (en) * 1937-04-02 1939-02-14 Rochester Mfg Co Inc Gauge damping construction
US3146851A (en) * 1961-08-17 1964-09-01 Arvin Ind Inc Sound attenuating gas conduit and resonators therefor
US3288371A (en) * 1964-04-22 1966-11-29 Arthur E Broughton Spray shower assembly with self-cleaning nozzle
US3375842A (en) * 1964-12-23 1968-04-02 Sperry Rand Corp Fluid diode
US3460577A (en) * 1966-06-24 1969-08-12 Sperry Rand Corp Spool type valve
US3718160A (en) * 1971-04-01 1973-02-27 Serva Soc Device for controlling air flow in ventilation pipes

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE530787A (enrdf_load_stackoverflow) * 1953-08-01
BE620300A (enrdf_load_stackoverflow) * 1961-08-01
US3279192A (en) * 1963-12-30 1966-10-18 Gen Electric Variable area exhaust nozzle
US3397860A (en) * 1966-04-19 1968-08-20 Case Co J I Valve for concrete pump or similar machine
GB1244292A (en) * 1970-01-14 1971-08-25 Rolls Royce Gas turbine engine

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1873138A (en) * 1930-09-24 1932-08-23 Mitchell James Macdonald Valve structure
US2147031A (en) * 1937-04-02 1939-02-14 Rochester Mfg Co Inc Gauge damping construction
US3146851A (en) * 1961-08-17 1964-09-01 Arvin Ind Inc Sound attenuating gas conduit and resonators therefor
US3288371A (en) * 1964-04-22 1966-11-29 Arthur E Broughton Spray shower assembly with self-cleaning nozzle
US3375842A (en) * 1964-12-23 1968-04-02 Sperry Rand Corp Fluid diode
US3460577A (en) * 1966-06-24 1969-08-12 Sperry Rand Corp Spool type valve
US3718160A (en) * 1971-04-01 1973-02-27 Serva Soc Device for controlling air flow in ventilation pipes

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4068469A (en) * 1975-05-29 1978-01-17 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Variable thrust nozzle for quiet turbofan engine and method of operating same
WO2008045057A1 (en) 2006-10-12 2008-04-17 United Technologies Corporation Bladder type variable area fan nozzle
US20100139240A1 (en) * 2006-10-12 2010-06-10 Glenn Levasseur Bladder type variable area fan nozzle
US8276364B2 (en) 2006-10-12 2012-10-02 United Technologies Corporation Bladder type variable area fan nozzle
US20180017020A1 (en) * 2015-02-11 2018-01-18 Mra Systems, Inc. Turbine engines with variable area nozzle
US10550797B2 (en) * 2015-02-11 2020-02-04 Mra Systems, Llc Turbine engines with variable area nozzle
CN107013268A (zh) * 2015-11-23 2017-08-04 通用电气公司 用于喷气发动机排气的压缩整流罩
CN107013268B (zh) * 2015-11-23 2020-03-06 通用电气公司 用于喷气发动机排气的压缩整流罩
US10920713B2 (en) 2015-11-23 2021-02-16 General Electric Company Compression cowl for jet engine exhaust

Also Published As

Publication number Publication date
DE2321432A1 (de) 1973-11-15
FR2182122A1 (enrdf_load_stackoverflow) 1973-12-07
DE2321432C2 (de) 1981-09-17
GB1418665A (en) 1975-12-24
JPS5723099B2 (enrdf_load_stackoverflow) 1982-05-17
JPS4954713A (enrdf_load_stackoverflow) 1974-05-28
IT980381B (it) 1974-09-30
FR2182122B1 (enrdf_load_stackoverflow) 1977-08-12

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